The present invention relates a system for conveying folded sheets in shingled relationship and in particular to folded sheets nested together into a common shingled stream.
In the printing industry such as the newspaper printing industry, it is conventional to place advertising inserts into newspapers. The inserts may be in the form of printed sheet items comprised of one or more folded sheets. The folded sheet items are stacked and later placed one at a time into newspapers. It is common in such operations to print duplicates of newspaper advertisements and the like and to nest the duplicates together as a folded sheet with one of the duplicate folded sheets having an exposed leading edge. Even when duplicates are not created in this manner, the output of a conventional printing press for folded sheets is a shingled stream of material which must be conveyed from the printing press to other locations such as a conventional stacking mechanism which rearranges the shingle stream into vertical stacks of folded items.
In order to convey the shingled stream from one place to the next, conveyors such as endless belt conveyors are frequently employed. Because it cannot be assumed that the destination for the shingled stream lies along a straight line at some distance from the printing press, such conveyor systems must often force the stream to make angled turns or in some cases 90.degree. turns depending upon plant configuration. For example, a 90.degree. turn in a conveyor system conveying a shingled stream of folded product is conventionally called a "bump" turn. Problems experienced with a typical bump turn include inconsistent shingle alignment and crooked delivery upon exit. This can cause jams at trimmer mechanisms which result from stream hesitation and the piling up of the product at the bump turn.
Sometimes the product stream needs to be realigned. That is, it is necessary to move the conveyor stream laterally but maintain the stream flow in essentially the same direction. Conventionally, flow turns and additional conveyors are needed to accomplish this function. Many of the problems associated with bump turns are also applicable to those experienced with stream realignment.
When product from the printing press is configured in nested relationship, as described above it, is frequently desirable to separate the nested product into two independent product streams. Machines for performing this function are commonly called deserters. An example of such a device is shown in U.S. Pat. No. 4,477,066 to Fischer, et al. The device shown in the Fischer patent extracts a nested folded sheet from a shingled stream by employing a nip roller which extends at an angle to the shingled stream which pinches a nonoverlapped sheet pulling it out to the side while conveyor belts continue to move the shingled stream, and the new stream consisting of the removed sheets, forward. The conveyor belts underneath the nip roller are oriented in a forward direction which means that the speed of the nip roller must be precisely set so that it includes a forward component of motion which exactly matches the speed of the conveyor belts. The problem with such a system is that the product is not always cleanly extracted and must still move crosswise to the conveyor belts. This can result in tearing, misalignment or bunching of the removed inserts from the shingled stream.